1. Field of the Invention
The present invention relates to a novel antenna system having increased capacity, easy assembly, fewer parts, high strength and the capability of enduring high wind-loads and low temperatures. This is accomplished by an antenna system comprising a closed ring of antenna panels supporting multiple lobes. The antenna system has a modular structure with exchangeable parts for economical transportation and manufacturing. The antenna system is easily adaptable to various conditions. The structural parts have an aerodynamic design and possible de-icing means for enduring severe climatic conditions.
The invention is related to the following patent applications with the same filing date as the present application or to be filed in the near future, having the same owner as the present application and entitled:
METHOD AND ARRANGEMENT OF CONVERTING A CELLULAR TELECOMMUNICATION SYSTEM; PA1 ROTATING LOBE ACCESS METHOD; PA1 SELF-SUPPORTING RADIO BASE STATION;
2. Discussion of the Background
The technological status of the analog cellular mobile telephony standard of today has a history going back to the late 70-ies. The present technology is a development of the systems from the early days.
The base stations are mostly omnidirectional sites (circular cells) or trisector sites (3.times.1200 cells). At the time of design it was considered to be enough with this cell structure. The antennas used are omnidirectional or 60.degree. sectorized antennas with low antenna gain requiring high power RF (Radio Frequency) transmitters in both the base station and in the mobile unit.
Existing cellular sites typically have 3 sides and each side has two receiving and two transmitting antennas spread out at a width of typically 3-6 meters, but each antenna and cell radio is only getting an effective use of 0.3.times.2.5 m with a width/height (W/H) ratio of 0.10-0.25. Thus only three different lobes and cells cover the horizon.
For a high capacity cellular antenna system it is much more important that the antenna has a wide diameter (=width) than it has height. Traditional cellular antennas typically are 0.3 m wide and 2.5-3.5 m high at 800/900 MHz or 0.7 m wide at 450 MHz and supports one 60.degree. lobe and a 120.degree. wide cell.
Thus, the prior art antenna systems typically have is high power consumption, high back lobes and high interference levels due to the reasons stated above.